Abstract: An automatic transfer switch comprising a pair of molded case switches, a novel cam drive mechanism and a lever linkage is provided to assure a programmed timed sequence of contact transfer so that arc extinction is achieved in load transfer and re-transfer between normal and emergency power sources, thereby preventing source to source short circuits. To prevent motor override from disturbing the cam during stopping, declutching or escapement means is provided to separate the drive pin in the cam plate from the motor drive. Improved transfer for motor loads may be achieved by additional escapement and time delay intervals in the transfer between normal and emergency sources. To facilitate the starting and stopping of the motor drive, auxiliary contact means are provided which coact with the outside periphery of the cam plate to open and to close the incoming power for the electric motor drive.